For a long time, pressure sensitive adhesives have been used for attaching medical devices, such as ostomy appliances, dressings (including wound dressings), wound drainage bandages, devices for collecting urine, orthoses and prostheses to the skin.
In connection with surgery for a number of diseases in the gastro-intestinal tract a consequence in many cases is, that the colon, the ileum or the urethra has been exposed surgically. The patient is left with an abdominal stoma and the effluents or waste products of the body, which are conveyed through these organs, are discharged through the artificial orifice or opening and are collected in a collection bag. The bag is usually adhered to the skin by means of an adhesive wafer or plate having an inlet opening for accommodating the stoma.
Traditionally, pressure sensitive adhesives used for an ostomy appliance are relatively hard hydrocolloid adhesives with a high tendency to strip the skin. The reason for this is that the adhesive should be able to withstand body movements and have a hydrocolloid content that is high enough to absorb moisture and sweat from the skin.
Optimal adhesives for an ostomy base plate have to perform under a variety of conditions, such as differences in fluidity and amount of stoma exudates, body shape, skin firmness, skin irregularities, activity and perspiration level, and of course the variation in the end-user's preferred changing pattern of the device.
An adhesive suitable for these applications should have a composition that is skin friendly in order to facilitate frequent changing. Furthermore, the adhesive should have a high moist absorption level and a high erosion resistance in order not to expose the skin to exudates from the stoma. Moreover, the adhesive should be flexible enough to adapt to the contours of the skin.
Adhesives such as described in WO 99/11302 perform well during perspiration. These adhesives typically have a high level of plasticity so that the adhesive will flow well to the skin after application. These adhesives have the disadvantage that they disintegrate during the contact with effluents from a stoma or a wound. The low tack of these adhesives makes the performance of the appliance sensible to how the user applies the product and usually requires that the user doesn't move around too much in a period immediately after application to avoid the adhesive from falling off. These types of adhesives are most often not flexible enough to fit well to hernias, skin folds and scars in the peristomal area. A poor fit to the skin will decrease the contact area between the appliance and the skin and greatly increase the risk of leakage. To make these adhesives more flexible the thickness could be lowered. This, however, will markedly reduce the adhesives overall capacity for absorbing perspiration, and because of the low tack, the sensibility of the application procedure will increase. Overall, these types of adhesives will not perform well in a flexible design.
Adhesives, such as described in U.S. Pat. No. 4,551,490 and WO 2007/082538, are usually more tacky and cohesive in the continuous phase compared to the adhesives described in WO 99/11302. This makes the continuous phase less prone to disintegration during the swelling of the hydrocolloids. The drawback of these adhesives is that the increased cohesiveness will reduce the absorption rate. Because the adhesives have a deficiency in plastic deformation, excessive swelling of the adhesives during contact with exudates will make them lose contact with the skin, resulting in the skin being exposed.
Therefore, these types of adhesives have lower initial overall water absorption. In order to perform in hot areas and/or on people with a high perspiration level, a certain amount of resin usually needs to be added. This will make the adhesives more aggressive and less skin friendly and therefore less suited for wear-times less than 48 hours.
An alternative to the absorbing adhesives described above is a liquid impermeable, moisture permeable adhesive such as polyurethane, silicone and polyacrylate. These adhesives are usually very soft and flexible and adapt well to skin fold and scars in the peristomal skin. However, they lack the ability of ion exchanging whereby the pH value of the skin is not maintained. The adhesives are often too soft to withstand contact with extrudes with low surface tension.
It has now surprisingly been found that by utilizing a soft permeable agent in combination with traditional hydrocolloid adhesives, such as described in WO 99/11302, an adhesive composition can be produced that is soft and tacky enough to adapt to skin contours such as scars and folds. Furthermore, it has improved erosion resistance, without compromising the moist absorption and ease of removal, nor introducing other possible adverse effects.